Enzymes are widely used in animal nutrition, with the purpose of increasing the bioavailability of certain nutrients or improving the feed conversion efficiency. Thus, for example, the enzyme phytase is used to release the phosphorus bound in phytate and thus ensure its bioavailability. It is further known to add NSP (nonstarch polysaccaride) enzymes to the feed in order, inter alia, to reduce the viscosity of the feed in the alimentary tract and thus improve the conversion efficiency of the feed.
However, feedstuffs containing an added enzyme preparation are frequently pelleted, expanded or extruded, as a result of which, owing to the resultant relatively high temperatures, the enzyme activity is reduced or completely destroyed. To avoid this disadvantage, enzymes in the form of liquid formulations are sprayed onto the already-pelleted feedstuff.
However, the use of liquid enzyme preparations also has disadvantages. Owing to the high water content or the high water activity, enzyme formulations of this type can be stabilized only with great difficulty. Frequently, a sharp drop in activity, an increase in microbial count and an impairment of the appearance of the preparation is observed during storage. In particular, owing to temperature fluctuations, precipitation of the enzymes or other proteins present therein may frequently be observed. In addition to the inadequate keeping quality, moreover, the low activity per unit volume is a serious disadvantage with liquid formulations.
WO 97/12958 discloses enzyme-containing microgranules which are obtained by agglomeration. They comprise an enzyme preparation applied to a support and at least one binder or decomposition accelerator. The granules are, in addition, polymer-coated and have a particle size of less than 0.4 mm. The enzyme content for a typical composition is less than 40% by weight. The preparation of an instant enzyme formulation which is suitable, in particular, as an easily handled feed additive is not described therein.
It is an object of the present invention therefore to provide an improved enzyme formulation which avoids the above-described disadvantages of liquid formulations.